Posts: 32935
Location: Rhinelander, Wisconsin | Just a point. HP is measured and listed at the prop now, not the crankshaft. If a motor is putting out 70 at the prop or 75 at the prop, top end will be faster with an exta 5 hp by about 2 mph if the prop they spin is the same and the motor weighs the same. Add 100 pounds, lose speed at about 3 mph on that boat all things considered. Don't know enough about the Yammys to know if they both spin the same prop, that will make a difference. Hole shot with more displacement may be offset by the extra 100 pounds, one needs to prop accordingly which then causes...loss in top end. I'd get in touch with Yamaha and ask them, they might be a little stronger in actual hp at the prop on the bigger block and dead on on the 70, which would cause me to lean toward the bigger motor. |
